MemberApril 9, 2021 at 3:01 pm
I have a customer wanting digital prints and vinyl graphics all over their windows and i read somewhere that this can cause windows to break or crack?
I “THINK” this was for black vinyl only but i am really not sure.
I have the customer coming in on monday and i now am worried that whatever i offer might cause cracks if i dont get the colour combination or coverage correct. can anyone help advise me on this?
MemberApril 9, 2021 at 4:45 pm
I’ve heard/read about this phenomenon previously. However I’ve never had it happen to me or know of anyone it has happened to.
I think the theory is based around black conducting heat during the day and then causing cracks as the temperature drops suddenly in the evening. Something like that anyway.
It doesn’t enter my thinking when planning window graphics to be honest.
MemberApril 9, 2021 at 6:26 pm
i havent given it a thought in all my days but the past 12 months I read it either here or someplace else and it now has me questioning myself.
this is a big window and several of them. they want either full coverage digital prints or text and blocked out with vinyl panels.
if it is a colour thing, I would just advise them on the issue and another colour would be used. but the uncertain side of it is concerning because I would really like this job due to the size of the company and the work that could follow. but no way could I cover the costs of the glass if anything happened.
Thanks for the reply david.
MemberApril 9, 2021 at 6:44 pm
Dark colours absorb heat whereas lighter colours reflect them. Black is obviously the worst and can cause the glass to get very hot. Have you ever put your hand on a black car or van that has been sitting in the sun? It’s the heat and consequent expansion that can cause the glass to break. Of course, it’s less of a problem now then it used to be as most windows are double glazed sealed units, but in the past many older windows were single glazed and held in place in wooden frames with putty and a few nails to hold the glass in place while the putty hardened. It was usually the nails being left in place that would start the crack.
But of course it is still a risk – and all you can do is explain the risk and the possible outcome making it clear that you would not be responsible for any breakage of glass caused in this way. If they are then still happy to go ahead then fine go ahead and do as they ask, it’s not your problem.
MemberApril 9, 2021 at 6:45 pm
Vinyl and uneven Thermal expansion can break glass, especially on south-facing glass.
It’s very unusual for it to happen, but you should cover yourself when quoting. It’s only a problem when it’s a problem. It can even happen with contravision
MemberApril 9, 2021 at 8:36 pm
I think it’s called Thermal shock fracture ( or similar), it was covered on here a good few years ago by a member who knew a fair bit about glass. Darker colours are the culprit but also how tightly the glass is fitted in the frame and if it’s been toughened, best to make the customer aware as discussed.
AdministratorApril 10, 2021 at 8:16 pm
AdministratorApril 10, 2021 at 8:28 pm
This video does not give a solution to thermal shock in glass with vinyl panels but does give some helpful insight to how common it can happen with things like shades, blinds and as uphill says, parameter fixings holding the glass.
MemberApril 12, 2021 at 5:14 pm
This happened to me in my old workshop. North facing (New Zealand North = South for you guys) The landlord was pretty clued up and made me pay for it. The glass was from the pre-toughening days, and the panes were very large so I remember it was expensive.
Nothing dramatic, I got back to the shop one day to find a large crack across the glass. Since then I always include a disclaimer if I do a window job, and make sure its understood and signed before proceeding.
MemberApril 13, 2021 at 11:09 am
@RobertLambie wow, I do not have a great shaped “car” like that! 😳🤣🤣
Thank you very much to everyone that has replied to my questions.
I will be honest, I still dont grasp exactly why this happens other than a greater build up of heat in the dark areas to lighter areas or areas with no vinyl, that causes a stress line causing a crack.
would i be right in saying this to my customer?
I have never worried about this, now i think i will constantly be paranoid doing window graphics. 🤨
MemberApril 13, 2021 at 12:22 pm
Personally i think you are worrying over nothing. Yes there is a chance of this happening however its highly unlikey and bringing it to your customers attention may lose you the job. If we were to start worrying about this on everything then theres hundreds of other things we should take into account. We would never get any work done. In the rare situation when you have an old single glass window, south facing and they want dark/black graphics over it then it might be worth mentioning.
Anyway thats my 10p worth
MemberApril 13, 2021 at 3:57 pm
As Martyn says, it’s rare. What happens is the dark colour absorbs the heat from the sun and makes the glass hot, the glass then tries to expand, as most things do when heated, but if fitted tight in the frame in hasn’t got anywhere to expand to, therefore the cracking.
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